From the looks of things early, Jarrod Parker was primed for quite a pitcher's duel with Cardinals ace Adam Wainwright.

Parker had some of his best stuff all season when he fell to the ground and grabbed his right hamstring in the fourth inning on an unusually hot Bay Area afternoon, forced into an early exit in Oakland's 7-1 loss to St. Louis on Saturday.

Parker stretched for several minutes with athletic trainer Nick Paparesta before throwing some warmup pitches to try to stay in the game. But manager Bob Melvin turned to Jesse Chavez.

"Tomorrow will be a better idea of what I've got," Parker said. "I've just been building on outings prior, and today everything was working good early. I was able to establish the fastball in and out. It was just unfortunate."

Parker will be re-evaluated Sunday.

"He wanted to try to finish the inning but he still felt it," manager Bob Melvin said. "It's not a prudent thing to do. The unfortunate thing was that might have been as good as stuff as he's had all year. Had a great changeup, had great velocity on the fastball, good movement, good slider. We might have been here a while had that not happened."

Wainwright tossed a five-hitter to become the NL's second 11-game winner, Matt Adams had his first two-homer game, and the St. Louis Cardinals beat the Oakland Athletics 7-1 Saturday.

Wainwright (11-5) tied Washington's Jordan Zimmerman for most wins in the NL. He struck out eight and walked two in a 112-pitch performance for his fourth complete game this year and 15th of his career.

He was enjoying the game with Parker early.

"That was fun, man," Wainwright said. "We were working quick."

Wainwright kept it up even once Parker was gone, and the Cardinals backed him up with plenty. Matt Adams hit a three-run homer to highlight a four-run sixth and a solo shot in the eighth for his first career multihomer game.

Wainwright knew how well the A's have been playing at home, and became determined to slow down the reigning AL West champions. With his signature, moving curveball, he kept them off-balance all day.

"He did a good job to hold us down the way he did," Josh Donaldson said. "Every time we seemed to get a guy on first base we hit into a double play. He's not going to be a guy that's going to overpower you. He's a very intelligent pitcher. Moves it, cuts it, sinks it, big curveball, changes speeds pretty well. He did his thing today."

Chavez (1-2), who pitched 5 2-3 scoreless innings of relief for victory in an 18-inning win against the Yankees on June 13, was done after 1 1-3 innings this time. Carlos Beltran doubled starting the sixth, and Allen Craig followed with a single to chase Chavez.

Jerry Blevins surrendered an RBI single to Matt Holliday, then Adams' first-pitch homer that broke open the game.

Daniel Descalso broke a scoreless tie with a sacrifice fly in the fifth, and the Cardinals gave Wainwright plenty of support to take sole possession of the team lead in wins ahead of Lance Lynn's 10.

After a 1-2-3 first inning on nine pitches, Wainwright was on his way. A's No. 9 hitter Derek Norris singled with two outs in the third for the first hit off Wainwright, who snapped a two-start skid.

Wainwright got through the seventh on seven pitches. The right-hander faced the A's for just the second time in his career after beating Oakland on June 19, 2010, in St. Louis while allowing one earned run in eight innings.

He had a career-high five complete games in 2010, and is now one away from that.

The A's were left wondering how it would have gone with Parker on the mound all day.

"If he could have stayed in the entire game we could still be playing 0-0 maybe," Donaldson said. "Who knows what would have happened. He really looked sharp early on. That's probably the best I've seen him all year early."

A sold-out Coliseum crowd of 35,067 braved the hot temperatures to watch Wainwright keep the A's batters off balance — they didn't get a three-ball count until Coco Crisp walked in the eighth as the 28th hitter of the game. Wainwright threw 21 of his pitches that inning.

While the first-pitch temperature was an A's season-high 84 degrees, Cardinals manager Matheny is loving the lively atmosphere this series.

"It reminds me of the Dominican and Puerto Rico, a lot of drums and excitement," he said.

Holliday faced repeated boos while in left field and at the plate from his former fans. He briefly played for the A's in 2009, all of 93 games.

NOTES: A's C John Jaso missed his seventh straight start with a cut on his left hand. ... A's C Stephen Vogt, who has filled in nicely for Jaso, received 100-plus text messages in addition to greetings on Facebook and Twitter after his first major league hit — and home run — Friday night ended an 0-for-33 start. "It's really neat to get everybody's support," he said. ... Umpires received water between innings. ... LHP Tommy Milone looks to snap a four-start winless stretch with his first win since June 3 in Sunday's finale against St. Louis RHP Jake Westbrook. ... Crisp is 4 for 31 over his last eight games after batting .361 in the previous 16.